How to Deploy a Django Project with Webpack on Railway?

Question

I'm deploying a Django project on Railway, and my `railway.json` looks like this:

```json
{
  "$schema": "https://railway.app/railway.schema.json",
  "build": {
    "builder": "NIXPACKS"
  },
  "deploy": {
    "startCommand": "python manage.py migrate && npm run build && python manage.py collectstatic --noinput --clear && gunicorn config.wsgi:application",
    "restartPolicyType": "ON_FAILURE",
    "restartPolicyMaxRetries": 10
  }
}
```

The project includes a build step for Webpack, but the deployment fails because Python isn't installed. It seems Nixpacks installs dependencies based on the commands provided, but I need both Python and Node.js for this project.

How can I configure Nixpacks to install both Python and Node.js?